The slide of the dollar has picked up new momentum as it breaks through a symbolic threshold.

The dollar weakened today to $1.40 against the euro, the highest level for the euro since its launch as a single currency in 1999.

The Federal Reserve's half-point cut in interest rates has prompted further selling of the dollar against other currencies.

"One thing that should be clear is that this is not a dollar-friendly Fed," Jim McCormick, the London-based global head of currency research at Lehman Brothers International, told Bloomberg News. "The biggest focus going forward is going to be the monetary policy expectations."

At the same time, the euro has been supported by indications that the European Central Bank will not be lowering interest rates and signs of stronger economic growth in Europe.  The euro is also being increasingly favored as a reserve currency.

In London trading, the dollar weakened to $1.4065 against the euro.  The dollar was also lower against the Japanese yen and the British pound.

Foreign exchange traders, as well as stock and bond traders, will be paying close attention today to comments from Ben Bernanke, the chairman of the Federal Reserve, when he testifies before the House Financial Services Committee.